Psycholinguistics & Neurolinguistics

Aphasia

Aphasia and its types

Aphasia?

Aphasia is the total or partial loss of language ability, specifically in reading, comprehension and / or writing, with preservation of the intelligence and integrity of the organs of phonation . The term was coined in 1864 by the French doctor Armand Trousseau.

Aphasia is a pathological state that degrades the faculty of language or speech as a result of lesions produced in cortical areas of language or in areas of cerebral association located in the left hemisphere of individuals. Based on the above, there are people who have difficulties in reading, writing, how they may have trouble speaking but keep their understanding intact.

Aphasia is caused by brain damage, due to a traumatic brain injury, progressive degeneration of brain cells located in the area of ​​language, stroke or stroke, the latter being the most frequent cause of aphasia. The latter is caused by the decrease in blood flow that a part of the brain receives or the rupture of blood vessels and the effusion caused by it, which causes the death of the neuron due to the lack of oxygen and nutrients.

Aphasia can be suffered by all people of different ages, social groups and sexes. This type of disorder can be suffered by infants during pregnancy or at the time of delivery, or acquired as a result of a brain injury between 2 years and 8-9 years. At this point, one can mention progressive primary aphasia is a degenerative neurological pathology, which begins with the production of language or its understanding, or both at the same time. Generally, it is suffered by people between 50 – 70 years of age.

Etymologically , the word is of Greek origin aphasia aphasia which means “the quality of not being able to speak”.

Causes of aphasia

The causes of aphasia are varied, but all occur in circumstances of brain injury:

  • Head injury
  • Tumors of the central nervous system
  • Stroke (most common cause of aphasia)
  • Degenerative diseases ( Alzheimer’s disease, Parkinson’s disease, etc.)
  • Localized or diffuse infections of the brain

Types of aphasia

The symptoms of aphasia depend both on the location of brain lesions and on the compensatory reactions of brain tissue that remain intact.

However, there are a number of common brain injuries that seem to group certain dysfunctions.

1. Broca’s aphasia or major motor aphasia

In  Broca’s Aphasia, deficits predominate in the motor aspects of language and writing, it is also accompanied by  agrammatism and in many cases, language comprehension disorders. Occasionally, sensory problems may appear on the right side and hemiparesis, which refers to a decrease in motor force or partial paralysis that affects a single arm or a single leg on the same side of the body.

This aphasia is the consequence of a large lesion that includes the cortical and subcortical elements along the frontal and superior portion of the Silvio fissure, including the insula; but its name comes from the implication that the lower frontal gyrus or  Broca’s area has in this disorder.

The most common causes of Broca’s aphasia may be:

  • Embolic occlusion of the superior division of the left middle cerebral artery
  • Frontal Lobe Abscess
  • Tumor Hypertensive putamen hemorrhage
  • Metastatic lesions
  • Subdural hematoma

During the evolution of Broca’s aphasia, the patient may be in an acute or subacute phase . While the acute phase occurs, the patient is practically mute, unable to understand and unable to communicate; also suffering a strong emotional impact. As the patient progresses, understanding begins to improve, while deficits in language and writing persist. As this improves, he is able to speak out loud, not without much slowness and effort.

Articulation and intonation are also affected, so that language becomes mainly a discourse of names and adjectives in which functional words such as articles, prepositions or conjunctions are omitted; becoming an agramatical and telegraphic language.

After the acute and subacute phases, speech difficulties may persist. However, a therapy in which language is worked can significantly improve the patient’s condition .

Finally, due to paralysis of the right hand, many patients cannot continue writing with it; so it requires a reeducation of writing with the left hand or take advantage of new technologies to enable communication.

2. Motor transcortical aphasia

This aphasia manifests problems similar to those of Broca’s aphasia. The main difference is that  transcortical motor aphasia exists a deficit in speech production, especially at the time of initiating a speech , in spontaneity or in its organization.

The articulatory aspect of speech does not usually present difficulties and the understanding of language remains intact, as is the production of names of places and people.

The cause of problems similar to those of Broca’s aphasia may be due to the fact that the genesis of the disorder is caused by a small subcortical lesion above the Broca area. At present, the implication of a circuit is suspected from the supplementary motor area, through the subcallosal fascicle to the  basal ganglia and the Broca area.

3. Wernicke’s aphasia

Wernicke’s aphasia is characterized by fluent speech but with a large number of substitutions and paraphasies , along with difficulties in understanding.

During the subacute phase, language comprehension is usually very deteriorated in serious cases, leading to absolute misunderstanding. However, speech is easy, clear and correctly articulated, and the contour of the rhythm is similar to that of normal speech. After these phases, auditory comprehension usually improves and the paraphasia is reduced.

If compared to Broca’s  aphasia, the functional words are present in Wernicke’s aphasia , but there are semantic and grammatical confusions. In addition, in this type of aphasia the motor area is intact so there is no paralysis on the right side, so patients can write, even though the content is disorganized and confusing, as is speech.

4. Driving aphasia

In this syndrome, what is seriously affected is repetition . Driving aphasia is a fluid aphasia with an almost normal understanding; but in which, in severe cases, fluency is severely compromised due to problems in the production of isolated words; thus becoming a sequential speech and short sentences.

Traditionally, it has been believed that this aphasia appeared as a result of an injury to the fibers that connect the Broca and Wernicke areas. But it has been discovered that there is also a relationship with lesions in the superior temporal gyrus and in the  insula .

In addition to the difficulties in repetition, these patients present problems when selecting words and in phonemic sequencing within individual words.

5. Global aphasia

People with global aphasia suffer from severe speech disorders, including fluency and comprehension problems ; So the communication is affected very strictly.

The most common cases are those that patients only manage to say a few words and their understanding of language is also very limited, since they cannot read or write either.

The most common cause of global aphasia is an injury that destroys a large part of the speech-related areas of the dominant hemisphere and is caused by obstruction of the left internal carotid artery or the middle cerebral artery.

6. Amnesic or anomic aphasia

Since anomia is a common characteristic of fluid aphasia, Wernicke and conduction aphasia, we will only talk about anomic aphasia when the difficulty of finding commonly used words appears in a relatively isolated way .

Aphasia treatment

It consists of attending therapies with a speech therapist who is in charge of prevention, evaluation and treatments for human communication disorders. Specifically, it is responsible for applying exercises to the type of aphasia suffered by the patient and applying the communication skills they have achieved in therapist sessions.

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